Recently, cracks in some gas turbine engine components were attributed to the directionally solidified grains therein having a primary crystal grain orientation that deviated from the [001] axis much further than expected. Therefore, there has become a need to be able to non-destructively determine the primary crystal grain orientation in directionally solidified and single crystal materials to ensure that the primary crystal grain orientation falls within certain limits of a predetermined crystal axis.
One conventional non-destructive method of determining the crystallographic orientations of single crystal materials, commonly known as the Laue method, involves directing x-rays onto the material, where they are reflected therefrom and/or therethrough and captured as an x-ray diffraction pattern, which can then be analyzed to determine the crystallographic orientations of the material. The Laue method, while capable of determining both the primary and secondary grain orientations of single crystal materials, is time consuming and cannot be easily utilized to determine the crystallographic orientations of various gas turbine engine components on-wing or in production environments, etc. Furthermore, the Laue method cannot be feasibly used on columnar-grained materials (i.e., directionally solidified materials) because it would be too expensive and too cumbersome to reorient the material with respect to the stacking axis to determine the crystallographic orientations of each individual grain therein.
Therefore, it would be desirable to have improved systems and methods for accurately and non-destructively determining the crystallographic orientations of directionally solidified and/or single crystal materials. It would be desirable if the crystallographic orientations of such materials could be determined based upon the measured velocity of ultrasonic surface skimming longitudinal waves thereon. It would also be desirable if such systems and methods could be easily used in various environments (i.e., on-wing, in production environments, in engine overhaul shops, etc.). It would be even further desirable if these velocity determining systems and methods could be used for other purposes, such as for sorting various materials, etc.